Image forming method

ABSTRACT

A method for forming an image with an ink-jet printer, the ink-jet printer being provided with: (i) a recording head having a plurality of nozzles; and (ii) a radiation means to irradiate an ink ejected on a recording media, wherein the method comprises the steps of: (a) ejecting droplets of the ink from the nozzles on the recording media, provided that: (1) the ink contains a cationic polymerizable monomer and a photo acid generating agent; (2) the recording media has a surface pH value of not less than 6; and (3) a volume of each droplets is from 2 to 10 pl, (b) irradiating the ejected droplets of the ink on the recording media within a period of time between 0.01 and 1.0 second after arrival of the droplets on the recording media.

TECHNICAL FIELD

[0001] The present invention relates to a method for forming an imageusing an ink-jet printer, in particular, a method which enables toproduce an image of high resolution.

BACKGROUND

[0002] In recent years, ink-jet recording methods have found wideapplication in the field of various kinds of graphic arts such asphotography, various kinds of printing, marking and specific printingsuch as color filters due to its ability to form images simply andcheaply. Particularly, it has also become possible to obtain imagequality comparable with silver salt photography by utilizing a recordingapparatus which ejects and controls minute dots; ink in which colorreproduction range, durability and ejection suitability have beenimproved; and exclusive paper in which ink absorption, color formingproperty of the colorant and surface gloss have been greatly enhanced.Image quality improvement of current ink-jet recording methods has beenachieved only when complete set of a recording apparatus, ink andexclusive paper are employed as a system.

[0003] However, an ink-jet system which requires exclusive paper isproblematic with respect to limitations of recording media and increasedcost of such recording media. Therefore, many attempts have been made torecord on a medium, on which ink is to be transferred, differing fromexclusive paper by means of ink-jet recording. Specifically, there arephase-conversion ink-jet methods utilizing wax which is solid at roomtemperature, solvent-type ink-jet methods utilizing an ink which iscomprised mainly of a rapid-drying organic solvent, and UV ink-jetmethods in which an ink is cross-linked by ultraviolet (UV) light afterrecording.

[0004] Among these, the UV ink-jet methods have been noted recently dueto rapid drying of prints and the capability of recording on a recordingmedium without ink absorptive property.

[0005] Such UV-curable ink-jet inks are disclosed in an examinedJapanese Patent Publication No. 5-54667, an unexamined publishedJapanese Patent Publication (JP-A) No. 6-200204, and Japanese translatedPCT Patent Publication No. 2000-504778. It is disclosed water-solublephoto-curable resin composition using a polymerizable compound having atleast two polymerizable functional groups and one or two anionicfunctional groups in the molecule. (e.g.: Patent documents 1 and 2)

[0006] Two types UV-curable ink-jet inks are known: one contains aradical polymerizable monomer; and the other contains a cationpolymerizable monomer. An ink containing a radical polymerizable monomertends to have a problem of odor due to a monomer and photoinitiator. Inaddition, it may have a problem of giving an increased shrinkage of anink layer after being polymerized.

[0007] On the other hand, an ink containing a cation polymerizablemonomer has an advantage of giving a small amount of odor; and theshrinkage of an ink layer is not large.

[0008] However, after our investigation it was found that, an inkcontaining a cation polymerizable monomer tends to decrease a hardeningproperty and adhesion ability when the surface pH value of the recordingmaterial is high.

[0009] [Patent document]

[0010] JP-A No. 2000-186243 (Claims of the invention)

[0011] [Patent document]

[0012] JP-A No. 2002-187918 (Claims of the invention)

SUMMARY

[0013] In view of the above-described problems, the present invention isattained. By using an ink which contains a cationic polymerizationmonomer, an image of high resolution can be achieved on a surface ofhigh pH value without deteriorating a hardening property andadhesiveness of the ink.

[0014] An object of the present invention is to provide a method whichenables to form an image of high resolution with a low amount of smell,high adhesiveness and a high hardening property.

[0015] The present invention can be achieved by the followingstructures.

[0016] An aspect of the present invention includes a method for formingan image with an ink-jet printer, the ink-jet printer being providedwith:

[0017] (i) a recording head having a plurality of nozzles; and

[0018] (ii) a radiation means to irradiate an ink ejected on a recordingmedia,

[0019] wherein the method comprises the steps of:

[0020] (a) ejecting droplets of the ink from the nozzles on therecording media, the ink containing a cationic polymerizable monomer anda photo acid generating agent; the recording media having a surface pHvalue of not less than 6; and a volume of each droplet being in a rangeof 2 to 10 pl,

[0021] (b) irradiating the droplets of the ink ejected on the recordingmedia within a period of time between 0.01 and 1.0 second after arrivalof the droplets on the recording media.

BRIEF DESCRIPTION OF DRAWINGS

[0022]FIG. 1 is a schematic front view showing a structure of an ink-jetprinter used for an image forming method of the present invention.

DETAILED DESCRIPTION

[0023] The present invention is achieved by finding an optimum conditionfor forming an image using a photo curable ink with an ink-jet printer.In order to obtain an optimum effect, the amount of each ink-jet dropletjetted from a nozzle of an ink-jet head, the timing of radiation afterreach of an ink droplet to a recording material and a composition of aphoto curable ink are adjusted.

[0024] The ink-jet head used for the present invention is preferablyprovided with a plurality of nozzles lined in a raw.

[0025] Another aspects of the present invention include the followingembodiments:

[0026] A method for forming an image with an ink-jet printer, whereinthe ink comprises a colorant.

[0027] A method for forming an image with an ink-jet printer, whereinthe recording media has a surface pH value of not less than 7.

[0028] A method for forming an image with an ink-jet printer, whereinthe cationic polymerizable monomer contained in the ink is an oxetanecompound.

[0029] A composition of a photo curable ink, a condition of forming animage with an ink-jet printer and a recording material for the presentinvention will be detailed below.

[0030] Examples of cationic polymerizable monomers (hereafter are alsoreferred to as cationic polymerizable photocurable resins) used in thepresent invention are such as UV curable pre-polymers of epoxy type (UVcurable monomer). Examples of UV curable monomers are compounds havingat least 2 epoxy groups in the molecule, e.g. alicyclic polyepoxide,polyglycidyl ester of polybasic acid, polyglycidyl ether of polyol,polyglycidyl ether of polyoxyalkylene glycol, polyglycidyl ester ofaromatic polyol, polyglycidyl ether of aromatic polyol, urethanepolyepoxy compound, and polyepoxy polybutadiene. Each of theaforementioned pre-polymers can be used solely or mixed with each other.

[0031] Other examples of cationic polymerizable monomers incorporated inthe cationic polymerizable composition are, (1) styrene derivatives; (2)vinylnaphthalene derivatives; (3) vinyl ethers; and (4) N-vinylcompounds, which are exemplified as below.

[0032] (1) Styrene Derivatives:

[0033] e.g. styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene,p-methyl-β-methylstyrene, α-methylstyrene and p-methoxy-β-methylstyrene.

[0034] (2) Vinyl Naphthalene Derivatives:

[0035] e.g. 1-vinylnaphthalene, α-methyl-1-vinylnaphthalene,β-methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene and4-methoxy-1-vinylnaphthalene.

[0036] (3) Vinyl Ethers:

[0037] e.g. isobutyl vinyl ether, ethyl vinyl ether, phenyl vinyl ether,p-methylphenyl vinyl ether, p-methoxyphenyl vinyl ether, α-methylphenylvinyl ether, β-methylisobutyl vinyl ether and β-chloroisobutyl vinylether.

[0038] (4) N-vinyl Compounds

[0039] e.g. N-vinylcarbazole, N-vinylpyrrolidone, N-vinylindole,N-vinylpyrrole, N-vinylphenothiazine, N-vinylacetoanilide,N-vinylethylacetoamide, N-vinylsuccinimide, N-vinylphthalimide,N-vinylcaprolactam and N-vinylimidazole.

[0040] In the present invention, at least one of the epoxy compounds ispreferably, an epoxy aliphatic acid ester or an epoxy aliphatic acidglyceride.

[0041] An oxetane compound of the present invention will be described.

[0042] <<A Compound Having a Substituent at the 2-position of theOxetane Ring in the Molecule>>

[0043] In the present invention, an oxetane compound has preferably anoxetane ring represented by General Formula (1) in the molecule.

[0044] wherein, R₁-R₆ each represents a hydrogen atom or a substituent,however, at least one of the groups represented by R3-R6 is asubstituent.

[0045] In General Formula (1), R₁-R₆ each represents a hydrogen atom, afluorine atom or an alkyl group having 1-6 carbon atoms (e.g., a methylgroup, an ethyl group, a propyl group or a butyl group), an fluorinatedalkyl group having 1-6 carbon atoms, an ally group, an aryl group (e.g.,a phenyl group, a naphtyl group, a furyl group or a thienyl group. Thesemay further have a substituent.

[0046] <<An Compound Having an Oxetane Ring in the Molecule>>

[0047] Among compounds represented by General Formula (1), a morepreferable compound is represented by General Formulas (2)-(5) describedbelow.

[0048] In General Formula (2) to (5), R₁-R₆ each represents a hydrogenatom or a substituent, R₇ and R₈ each represents a substituent, Zrepresent independently an oxygen atom or a sulfur atom, or a divalenthydrocarbon group which may have an oxygen atom or a sulfur atom in themain chain.

[0049] In General Formula (2) to (5), the substituents represented byR₁-R₆ designate the same substituent as by R₁-R₆ in General Formula (1).

[0050] R₇ and RB₈ in General Formula (2) to (5) each represents an alkylgroup having 1-6 carbon atoms (e.g., a methyl group, an ethyl group, apropyl group or a butyl group), an alkenyl group having 1-6 carbon atoms(e.g., a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenylgroup, a 2-methyl-2-propenyl group, a 1-butenyl group, a 2-butenylgroup, or a 3-butenyl group), an aryl group (e.g., a phenyl group, abenzyl group, a fluorobenzyl group, a methoxybenzyl group or aphenoxybenzyl group), an alkylcarbonyl group having 1-6 carbon atoms(e.g., a propylcarbonyl group, a butylcarbonyl group, or apentylcarbonyl group), an alkoxycarbonyl group having 1-6 carbon atoms(e.g., an ethoxycarbonyl group, a propoxycarbonyl group, or abutoxycarbonyl group), an alkylcarbamoyl group having 1-6 carbon atoms(e.g.,a propylcarbamoyl group or a butylpentylcarbamoyl group, or analkoxy carbamoyl group having 1-6 carbon atoms (e.g., an ethoxycarbamoylgroup).

[0051] Listed examples of Z in General Formulas (2) to (5) are, analkylene group (e.g. ethylene group, trimethylene group, tetramethylenegroup, propylene group, ethylethyelene group, pentamethyelene group,hexamethyelene group, heptamethylene group, octamethylene group,nanomethyelene group, decamethyelen group); an alkenylene group (e.g.vinylene group, propenylene group); and an alkynylene group (e.g.ethynylene group, 3-pentynylene group). The carbon atom in theaforementioned alkylene group, alkenylene group and alkynylene group maybe replaced with an oxygen atom or a sulfur atom.

[0052] Among the substituents mentioned above, a preferable group for R₁is a lower alkyl group (e.g. methyl group, ethyl group, and propylgroup), a more preferable group is an ethyl group.

[0053] Preferably groups for R₇ and R₈ are, propyl group, butyl group,phenyl group or benzyl group.

[0054] Z is preferably a hydrocarbon group without containing an oxygenatom or a sulfur atom (e.g. alkylene group, alkenylene group oralkynylene group).

[0055] <<An Oxetane Compound Having at Least Two Oxetane Groups in theMolecule>>

[0056] In the present invention, a compound represented by GeneralFormulas (6) and (7) described below can be used.

[0057] In General Formulas (6) and (7), Z designates the same as Z inFormulas (2) to (5); and m represents 2, 3, or 4.

[0058] R₁-R₆ each represents a hydrogen atom, a fluorine atom or analkyl group having 1-6 carbon atoms (e.g., a methyl group, an ethylgroup, a propyl group or a butyl group), an fluorinated alkyl grouphaving 1-6 carbon atoms, an ally group, an aryl group, a furyl group. InGeneral Formulas (6), at least one of R₃-R₆ is a substituent.

[0059] R₉ represents a straight or branched alkylene group having 1-12carbon atoms, or a divalent group represented by General Formulas (9),(10) or (11).

[0060] Examples of branched alkylene groups having 1-12 carbon atoms arerepresented by General Formula (8) described below.

[0061] wherein R₁₀ represents a lower alkyl group (e.g., a methyl group,an ethyl group, or a propyl group).

[0062] In General Formula (9), n represents 0 or an integer of 1-2,000,R₁₁ represents an alkyl group having 1-10 carbon atoms or the grouprepresented by General Formula (12) described below.

[0063] R₁₂ represents an alkyl group having 1-10 carbon atoms (e.g., amethyl group, an ethyl group, a propyl group, a butyl group.

[0064] In General Formula (12), j represents 0 or an integer of 1-100,and R₁₃ represents an alkyl group having 1-10 carbon atoms (e.g., amethyl group, an ethyl group, a propyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group, an octyl group, or a nonyl group).

[0065] In General Formula (10), R₁₄ represents a hydrogen atom, an alkylgroup having 1-10 carbon atoms (e.g., a methyl group, an ethyl group, apropyl group, a butyl group), an alkoxy group having 1-10 carbon atoms(e.g. a methoxy group, an ethoxy group, a propoxy group, a butoxy group,and a pentoxy group), a halogen atom (e.g., a fluorine atom, a chlorineatom, a bromine atom, or an iodine atom), a nitro group, a cyano group,a mercapto group, an alkoxycarbonyl group of lower alkyl number (e.g., amethyloxycarbonyl group, an ethyloxycarbonyl group, or abutyloxycarbonyl group), or a carboxyl group.

[0066] In General Formula (11), R₁₅ represents an oxygen atom, a sulfuratom, —NH—, —SO—, —SO₂—, —CH₂—, —C(CH₃)₂—, or —C (CF₃)₂—.

[0067] Embodiments of the preferred partial structure of compoundshaving an oxetane ring employed in the present invention are as follows.For example, in aforesaid General Formulas (6) and (7), R₁ is preferablya lower alkyl group (e.g., a methyl group, an ethyl group, or a propylgroup), and is more preferably an ethyl group. Further, preferablyemployed as R₉ is a hexamethylene group or a group in which R₁₄ is ahydrogen atom in aforesaid General Formula (10).

[0068] In aforesaid General Formula (8), it is preferable that R₁₀ is anethyl group, R₁₂ and R₁₃ each is a methyl group, and Z is a hydrocarbongroup which contains neither an oxygen atom nor a sulfur atom.

[0069] Further, listed as one example of preferred embodiments ofcompounds having an oxetane ring according to the present invention isthe compound represented by General Formula (13) described below.

[0070] wherein r represents an integer of 25-200; R₁₆ represents analkyl group having 1-4 carbon atoms (e.g., a methyl group, an ethylgroup, a propyl group, or a butyl group), or a trialkylsilyl group; R₁,R₃, R₅, and R₆ each is the same as a substituent represented by each ofR₁-R₆ in aforesaid General Formula (1), however, at least one of R₃-R₆is a substituent.

[0071] Specific examples of compounds having an oxetane ring, in whichposition 2 is substituted, are shown as Exemplified Compounds 1-13.However, the present invention is not limited thereto.

[0072] 1: trans-3-tert-butyl-2-phenyloxetane

[0073] 2: 3,3,4,4-tetramethyl-2,2-diphenyloxetane

[0074] 3: di[3-ethyl(2-methoxy-3-oxetanyl)]methyl ether

[0075] 4: 1,4-bis(2,3,4,4-tetramethyl-3-ethyl-oxetanyl)butane

[0076] 5: 1,4-bis(3-methyl-3-ethyloxetanyl)butane

[0077] 6: di(3,4,4-trimethyl-3-ethyloxetanyl)methyl ether

[0078] 7: 3-(2-ethyl-hexyloxymethyl)-2,2,3,4-tetramethyloxetane

[0079] 8: 2-(2-ethyl-hexyloxy)-2,3,3,4,4-pentamethyl-oxetane

[0080] 9: 4,4′-bis[(2,4-dimethyl-3-ethyl-3-oxetanyl)methoxy]biphenyl

[0081] 10: 1,7-bis(2,3,3,4,4-pentamethyl-oxetanyl)heptane

[0082] 11: oxetanyl silsesquioxane

[0083] 12: 2-methoxy-3,3-dimethyloxane

[0084] 13: 2,2,3,3-tetramethyloxetane

[0085] 14: 2-(4-methoxyphenyl)-3,3-dimethyloxetane

[0086] 15: di[2-(4- methoxyphenyl)-3-methyloxetane-3-yl]ether

[0087] It is possible to synthesize the compounds according to thepresent invention, which have an oxetane ring in which at least position2 is substituted, with reference to publications described below.

[0088] (1) Hu Xianming, Richard M. Kellogg, Synthesis, 533-538, May(1995)

[0089] (2) A. O. Fitton, J. Hill, D. Ejane, R. Miller, Synth., 12, 1140(1987)

[0090] (3) Toshiro Imai and Shinya Nishida, Can. J. Chem. Vol. 59,2503-2509 (1981)

[0091] (4) Nobujiro Shimizu, Shintaro Yamaoka, and Yuho Tsuno, Bull.Chem. Soc. Jpn., 56, 3853-3854 (1983)

[0092] (5) Walter Fisher and Cyril A. Grob, Helv. Chim. Acta., 61, 2336(1987)

[0093] (6) Chem. Ber. 101, 1850 (1968) (7) “Heterocyclic Compounds withThree- and Four-membered Rings”, Part Two, Chapter IX, IntersciencePublishers, John Wiley & Sons, New York (1964)

[0094] (8) Bull. Chem. Soc. Jpn., 61, 1653 (1988)

[0095] (9) Pure Appl. Chem., A29 (10), 915 (1992)

[0096] (10) Pure Appl. Chem., A30 (2 & amp;3), 189 (1993)

[0097] (11) Japanese Patent Application Open to Public Inspection No.6-16804

[0098] (12) DE 10221858

[0099] (Content in Photocurable Ink)

[0100] The amount of compounds according to the present invention, whichhave an oxetane ring in which at least position 2 is substituted, in aphotocurable ink is preferably 1-97 percent by weight, and is morepreferably 30-95 percent by weight.

[0101] (Use of Oxetane Compounds in Combination with Other Monomers)

[0102] Further, compounds according to the present invention, which haveoxetane ring(s) in which at least position 2 is substituted, may beemployed individually or in combinations with two types which havedifferent structures. Further, the aforesaid compound may be employed incombination with photopolymerizable compounds such as photopolymerizablemonomers or polymerizable monomers described below. When employed incombinations, it is preferable that a mixture is prepared so that theamount of compounds having oxetane ring(s) in the aforesaid mixture isadjusted to 10-98 percent by weight. Still further, it is preferablethat the amount of other photopolymerizable compounds such asphotopolymerizable monomers and polymerizable monomers is adjusted to2-90 percent by weight.

[0103] <<An Oxetane Compound Having a Substituent only at the 3-positionof the Oxetane Ring in the Molecule>>

[0104] In the present invention, a known oxetane compound can be used incombination with an oxetane compound having a substituent at the2-position. Preferable oxetane compound is an oxetane compound having asubstituent only at the 3-position of the oxetane ring in the molecule.

[0105] Examples of an oxetane compound having a substituent only at the3-position of the oxetane ring in the molecule are disclosed in JP-ANos. 2001-220526 and 2001-310937.

[0106] An oxetane compound having a substituent only at the 3-positionof the oxetane ring in the molecule is represented by General Formula(14).

[0107] In the General Formula (14), R¹ is a hydrogen atom, alkyl grouphaving 1-6 carbon atoms such methyl group, ethyl group, propyl group orbutyl group, fluoro-alkyl group having 1 to 6 carbon atoms, allyl group,aryl group, furyl group, or thienyl group. R² is an alkyl group having 1to 6 carbon atoms such as methyl group, ethyl group, propyl group orbutyl group; alkenyl group having 2 to 6 carbon atoms such as 1-propenylgroup, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenylgroup, 1-butenyl group, 2-butenyl group or 3-butenyl group; a grouphaving aromatic ring such as phenyl group, benzyl group, fluoro-benzylgroup, methoxy-benzyl group or phenoxy-ethyl group; alkyl carbonyl grouphaving 2 to 6 carbon atoms such as ethyl carbonyl group, propyl carbonylgroup or butyl carbonyl group; alkoxy carbonyl group having 2 to 6carbon atoms such as ethoxy carbonyl group, propoxy carbonyl group orbutoxy carbonyl group; N-alkyl carbamoyl group having 2 to 6 carbonatoms such as ethyl carbamoyl group, propyl carbamoyl group, butylcarbamoyl group or pentyl carbamoyl group. As the oxetane compound usedin the present invention, it is particularly preferable that thecompound having one oxetane ring is used, because the obtainedcomposition is excellent in the coking property, and the operability isexcellent in the low viscosity.

[0108] Next, as the compound having two oxetane rings, the compoundsshown by the following General Formula (15) are listed.

[0109] In the General Formula (15), R¹ is the same group as the groupshown in the above-described General Formula (14). R³ is, for example, alinear or branching alkylene group such as ethylene group, propylenegroup or butylene group; linear or branching poly (alkylene-oxy) groupsuch as poly (ethylene oxy) group or poly (propylene oxy) group; linearor branching un-saturated hydrocarbon group such as propenylene group,methyl propenylene group or butenylene group; carbonyl group; alkylenegroup including carbonyl group; alkylene group including carboxyl group;alkylene group including carbamoyl group.

[0110] Further, R³ may also be a polyvalent group selected from thegroup shown by the following General Formulas (16), (17) and (18).

[0111] In the General Formula (16), R⁴ is a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms such as methyl group, ethyl group,propyl group or butyl group, or alkoxy group having 1 to 4 carbon atomssuch as methoxy group, ethoxy group, propoxy group or butoxy group, orhalogen atom such as chloride atom or bromine atom, nitro group, cyanogroup, mercapto group, lower alkyl carboxyl group such as the grouphaving 1 to 5 carbon atoms, carboxyl group, or carbamoyl group.

[0112] In the General Formula (17), R⁵ is oxygen atom, sulfide atom,methylene group, —NH—, —SO—, —SO₂—, —C(CF₃)₂—, or —C (CH₃)₂—.

[0113] In the General Formula (18), R⁶ is an alkyl group having 1 to 4carbon atoms such as methyl group, ethyl group, propyl group or butylgroup, or aryl group. Numeral n is an integer of 0-2000. R⁷ is an alkylgroup having 1 to 4 carbon atoms such as methyl group, ethyl group,propyl group or butyl group, or aryl group. R⁷ is also a group selectedfrom the group shown by the following General Formula (19).

[0114] In the General Formula (19), R⁸ is an alkyl group having 1 to 4carbon atoms such as methyl group, ethyl group, propyl group or butylgroup, or aryl group. Numeral m is an integer of 0-100.

[0115] As a specific example of the compound having 2 oxetane rings, thecompounds shown by the following structural formulas are listed.

[0116] Exemplified compound 1 shown by the above structural formula is acompound in which R¹ is an ethyl group, and R³ is a carboxy group inGeneral Formula (15).

[0117] Exemplified compound 2 shown by the above structural formula is acompound in which each R⁶ and R⁷ are a methyl group, and n is 1 GeneralFormula (18).

[0118] Among the compound having 2 oxetane rings, as a preferableexample except for the above-described compounds, there are compoundsshown by the following General Formula (20). In the General Formula(20), R¹ is the same group as in the General Formula (14).

[0119] As the compounds having 3-4 oxetane rings, the compounds shown inthe following General Formula (21) are listed.

[0120] In the General Formula (21), R¹ is the same group as in theGeneral formula (14). R⁹ is, for example, a branching alkylene grouphaving 1 to 12 carbon atoms such as groups shown by the followingFormulas A-C, or a branching poly(alkylene oxy) group such as groupshown by the following Formula D.

[0121] In Formula A, R¹⁰ is a lower alkyl group such as a methyl, ethyl,or propyl group. In Formula D, p is an integer of 1 to 10.

[0122] As the specific example of the compound having 3 to 4 oxetanerings, the compound shown in the following Exemplified compound 3 iscited.

[0123] Furthermore, as an example of the compounds having 1-4 oxetanerings except the above examples, there are compounds shown in thefollowing General Formula (22).

[0124] In the General Formula (22), R⁸ is the same group as in theGeneral Formula (19). R¹¹ is alkyl group having 1 to 4 carbon atoms suchas methyl group, ethyl group, propyl group or butyl group, or tri-alkylsilyl group, and numeral r is 1-4.

[0125] As preferable specific examples of the oxetane compounds used inthe present invention, there are compounds 4-6 shown below.

[0126] The production method of the compounds having the oxetane ring isnot particularly limited, and it may be conducted according to theconventionally known method, and for example, there is a syntheticmethod of an oxetane ring from diol disclosed by Pattison (D. B.Pattison, J. Am. Chem. Soc., 3455, 79 (1957)).

[0127] Further, other than them, compounds having 1-4 oxetane rings,which have high molecular weight of molecular weight of about 1000-5000,are also listed. As an example of them, for example, the followingcompounds 7-9 are listed.

[0128] A photo acid generating agent used in the present invention isdetailed below.

[0129] As a photo acid generating agents, the compounds used for thechemical amplification type photo resist or photo cation polymerizationis used (Organic electronics material study group edition, “Organicmaterial for imaging” Bunshin publication co., (1993), refer to page187-192). Examples of the compounds preferable for the present inventionwill be listed below.

[0130] Example compounds used for the present invention are cited below.

[0131] Initially, the salt such as B(C₆F₅)₄ ⁻, PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻,CF₃SO3⁻ of the aromatic onium compound such as diazonium, ammonium,iodonium, sulfonium, phosphonium, can be listed.

[0132] Borate compounds are preferred due to high capacity to produceoxygen atom. Specific example of onium compound, which can be used inthe present invention, will be shown blow.

[0133] Secondly, the sulfonic compound generating the sulfonic acid canbe listed. Its specific compound will be illustrated below.

[0134] Thirdly, the halide compound generating the hydrogen halide canalso be used. Its specific compound will be illustrated below.

[0135] Fourthly, an iron π complex (ferrocene) can be listed.

[0136] When ink according to the present invention is colored, colorantsare incorporated.

[0137] Employed as colorants usable in the present invention may beconventionally known pigments and dyes. Listed as pigments may be, forexample, various organic chromatic color pigments such as phthalocyaninebased, azo based, quinacridone based, dioxanzine based, ordiketopyropyrrole based pigments, and inorganic pigments such as carbonblack, titanium white, silica, mica, and zinc oxide.

[0138] Suitably employed as organic pigments may be those listed below.Examples of yellow pigments include Pigment Yellow Pigment 1, PigmentYellow 2, Pigment Yellow 3, Pigment Yellow 12, Yellow 13, Pigment Yellow14, Pigment Yellow 16, Pigment Yellow 17, Pigment Yellow 55, PigmentYellow 73, Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83,Pigment Yellow 93, Pigment Yellow 95, Pigment Yellow 97, Pigment Yellow98, Pigment Yellow 109, Pigment Yellow 110, Pigment Yellow 114, PigmentYellow 128, Pigment Yellow 138, Pigment Yellow 139, Pigment Yellow 150,Pigment Yellow 151, Pigment Yellow 154, Pigment Yellow 155, and PigmentYellow 180.

[0139] Listed as magenta pigments are, for example, Pigment Red 5,Pigment Red 7, Pigment Red 12, Pigment Red 48 (Ca), Pigment Red 48 (Mn),Pigment Red 57:1, Pigment Red 57 (Sr), Pigment Red 57:2, Pigment Red122, Pigment Red 123, Pigment Red 146, Pigment Red 168, Pigment Red 184,Pigment Red 202, Pigment Red 221, Pigment Red 238, and Pigment Violet19.

[0140] Listed as cyan pigments are, for example, Pigment Blue 1, PigmentBlue 2, Pigment Blue 3, Pigment Blue 16, Pigment Blue 22, Pigment Blue60, Pigment Blue 15:2, Pigment Blue 15:3, Pigment Blue 15:4, Vat Blue 4,and Vat Blue 60.

[0141] When pigments are used as a colorant, it is preferable thatwater-based pigment dispersion in which the above pigments are uniformlydispersed into a water-based medium is employed and the resultingdispersion is mixed with water-soluble photocuring type resinouscomposition according to the present invention. It is also preferable touse water-based pigment dispersion in which pigments are stablydispersed in water by an anionic functional group. For example, it ispossible to employ, without any modifications, water-based gravure ink,water-based writing pigment dispersion, and conventional prior artpigments dispersions for ink jet ink, which are stable in a nonionicsystem or an anionic system.

[0142] Pigment dispersions which are dispersed by alkali-solublewater-soluble polymers having an anionic dissociation group aredisclosed, for example, in JP-A Nos. 5-247392 and 8-143802. Further, apigment dispersion which is dispersed by surface active agents having ananionic dissociation group is disclosed in JP-A No. 8-209048. Stillfurther, pigment dispersions which are dispersed in such a manner thatencapsulation is carried out employing polymers and an anionicdissociation group is provided on the resulting surface are disclosed inJP-A Nos. 10-140065, 9-316353, 9-151342, 9-104834, and 9-31360. Stillfurther, there are dispersions as disclosed in U.S. Pat. Nos. 5,837,045and 5,851,280, in which pigment dispersions are prepared by dispersingpigments while combining an anionic dissociation group onto the surfaceof the pigments via chemical reaction.

[0143] Basic requirements for stable pigment dispersion which can beused for an ink jet recording ink are as follows. Pigments are dispersedin a water-based medium, and the particle size distribution in theresulting dispersion is 25 350 nm in terms of average particle diameter,the viscosity of the final ink is controllable in a range whichadversely affect ink injection, and further, compatibility is satisfiedwith essential compounds which make the ink ultraviolet radiationcurable.

[0144] Further, by controlling the average particle diameter of pigmentparticles in the range of about 35 nm-about 350 nm, which is less thanthe wavelength of visible light, printed matter with the desiredtransparency is provided under minimal scattered light, even thoughtransparency varies depending on the use of the printed matter.

[0145] When pigments are employed as a colorant of ink, theconcentration of the portion of genuine pigments is customarily in therange of 0.3-15 percent by weight of the total ink. Tinting strength ofpigments depends on the dispersion state of the pigment particles.Concentration in the range of about 0.3-1 percent by weight refers tothe range in which the ink is used as a pale ink. When the concentrationexceeds the above range, density used for common tinting results.

[0146] Further, the composition ratio of the ink jet ink employed in thepresent invention is determined employing a pigment dispersion so thatthe viscosity of the ink composition reaches 10-500 mPa·s at 25° C. and1-30 mPa·s when heated to at least 35° C.

[0147] By enhancing the viscosity at room temperature, it is possible tominimize ink penetration even into absorptive recording medium, todecrease uncured monomers, and to reduce unpleasant odors, as well as tominimize dot bleeding during deposition of ink droplets, whereby imagequality is improved. Further, similar dots are formed on recording mediaexhibiting different surface tension, whereby similar image quality isachieved. When the viscosity is less than 10 mPa·s, the resultingbleeding resistant effect is minimal, while when it exceeds 300 mPa·s,feeding of ink liquid results in problems.

[0148] Further, in order to achieve stable ejection, it is preferablethat the viscosity of the ink composition is 1-30 mPa·s.

[0149] During preparation of the ink of the present invention, employedraw materials may be mixed in any order. However, in order to assurestability during mixing, it is preferable that all the materials arepreviously regulated to be neutral or basic. During mixing, it ispreferable to rapidly stir a mixture so that a non-uniform state is notmaintained over an extended period. When a pigment dispersion isemployed as a colorant, it is preferable that after mixing, theresulting mixture is well stirred so that uniformity is maintained.

[0150] An image forming method will now be described.

[0151] In the image forming method employing the ink of the presentinvention, after allowing the ink composition to adhere to a recordingmedium, it is exposed to actinic radiation is exposed. Radiationexposure may be either visible light exposure or ultraviolet radiationexposure. However, ultraviolet radiation exposure is particularlypreferred. When ultraviolet radiation is exposed, the exposure amount isat least 100 mJ/cm², is preferably at least 500 mJ/cm² and at most10,000 MJ/cm², and preferably in the range of at most 5,000 mJ/cm². Anultraviolet exposure amount in the range specified as above isadvantageous because it makes it possible to sufficiently proceed with acuring reaction, and it is also possible to minimize discoloration ofcolorants due to ultraviolet radiation exposure. Listed as ultravioletradiation sources are metal halide lamps, xenon lamps, carbon arc lamps,chemical lamps, low pressure mercury lamps, and high pressure mercurylamps. For example, it is possible to use commercially availableradiation sources such as H lamp, D lamp, or V lamp, manufactured byFusion System Co.

[0152] Metal halide lamps emit continuous spectral radiation compared tohigh pressure mercury lamps (at a dominant wavelength of 365 nm),exhibit high emission efficiency in a range of 200-450 nm, and emitabundant radiation in the long wavelength region. Accordingly, whenpigments are employed, as ink compositions of the present invention, theabove metal halide lamps are suitable.

[0153] In the present invention, after deposition of ink droplets onto arecording material and subsequently curing of the resulting ink, thethickness of the total ink layer is preferably 2-20 μm. In actinicradiation curable type ink jet recording in the screen printing field,at present, the thickness of the total ink layer exceeds 20 μm. In thesoft package printing field in which recording materials are oftencomprised of thin plastic materials, in addition to the above-mentionedproblems of curling and wrinkling of recording materials, problems occurin which stiffness and feel of quality of the entire printed mattervary. Consequently, excessive ink ejection, which results in a thicklayer, is not preferred.

[0154] “Thickness of the total ink layer”, as described herein, refersto the maximum value of the thickness of an ink layer formed on arecording material. Even when recording is carried out employing an inkjet recording system of a single color, and other 2-color overlapping(secondary color), 3-color overlapping, and 4-color overlapping (whiteink base), the thickness of the total ink layer is as defined above.

[0155] In view of ink ejection stability, ink ejection conditions arethat recording heads as well as the ink are heated 35-100° C., andsubsequently the ink is ejected. An actinic radiation curable inkresults in a wide viscosity variation range depending on temperaturevariation. To a large extent, viscosity variation directly affects thesize of liquid droplets and the rate of liquid droplet ejection, whichdegrades image quality. Consequently, it is necessary to maintain inktemperature even when heated. The control range of the desired inktemperature is commonly set temperature ±5° C., is preferably settemperature ±2° C., and is more preferably set temperature ±1° C.

[0156] Further, in the present invention, the volume of a liquid dropletejected from each of the ejection outlets of a recording head ispreferably 2-15 pl. Originally, in order to form highly detailed images,it is necessary that the volume of a droplet is within theabove-mentioned range. When ejection is carried out at this volume of adroplet, it becomes particularly difficult to maintain theabove-mentioned ejection stability. According to the present invention,even when ejection is carried out employing a small volume of liquid inkdroplets such as 2-15 pl, it is possible to enhance ejection stabilityand to stably form highly detailed images.

[0157] In the image forming method of the present invention, exposureconditions to actinic radiation are that actinic radiation is exposedpreferably 0.01-1.0 second after ink deposition, and more preferably0.01-0.5 second after ink deposition.

[0158] A basic method of actinic radiation exposure methods isdisclosed, for example, in JP-A No. 60-132767. According to the above,radiation sources are provided on both sides of a head unit, and thehead and the radiation source are scanned employing a shuttle system.Exposure to actinic radiation is carried out the specified time afterink deposition. Further, curing is completed employing another radiationsource which is not driven. U.S. Pat. No. 6,145,979 discloses a methodwhich employs optical fiber as an exposure method for actinic radiation,and a method in which UV radiation is exposed to a recording sectionwhile allowing a collimated radiation source to be incident to themirror surface provided on the side of a head unit. In the image formingmethod of the present invention, it is possible to use any of theseexposure methods.

[0159] Further, the following method is also one of the preferredembodiments. Exposure to actinic radiation is divided into two stages.Initially, actinic radiation is exposed 0.01-1.0 second after inkdeposition employing the above-mentioned method and after finishingprinting of the entire sheet, it is further exposed to actinicradiation. By dividing exposure to actinic radiation into two stages, itis possible to minimize contraction of recording materials, which occursduring curing the ink.

[0160] Supports for the present invention are explained. In thisinvention, various types of non-absorptive supports can be used otherthan common coated paper and non-coated paper.

[0161] Examples of various types of plastic films including PET(polyethylene terephthalate) film, OPS (oriented polystyrene) film, OPP(oriented polypropylene) film, ONy (oriented nylon) film, PVC (polyvinylchloride) film, PE film, and TAC film. Employed as other plastic filmsmay be polycarbonate, acrylic resins, ABS, acetal, PVA, and rubber.Further, metal and glass may also be employed.

[0162] When cationic curable ink is used for printing on theabove-described supports having a surface pH value of not less than 6.0,there may occur problems of insufficient hardening, decrease ofadhesiveness or ink bleeding. In the present invention, a method ofprinting without such problems even on a surface pH value of not lessthan 6.0. Further, the present invention is more effective in printingon a surface pH value of not less than 7.0. The surface pH value of thisinvention can be obtained as follows:

[0163] (i) putting 0.1 ml of water on a surface of sample, the samplebeing kept at 23° C. with 48% RH;

[0164] (ii) left 5 minutes; then

[0165] (iii) measuring the pH.

[0166] In the present invention, form the viewpoint of the cost ofrecording materials such as packaging cost as well as production cost,print production efficiency, and compatibility with prints of varioussizes, it is more advantageous to used long (web) recording materials.

[0167] The recording apparatus employed in the present invention willnow be described with reference to a drawing when deemed necessary.Further, the recording apparatus in the drawing is one of theembodiments employed in the present invention, but the recordingapparatus employed in the present invention is not limited thereto.

[0168]FIG. 1 is a front view showing the structure of the main sectionof the recording apparatus employed in the present invention. Recordingapparatus 1 is comprised of head carriage 2, recording head 3,illumination means 4, and platen section 5. Platen section 5 exhibits anultraviolet radiation absorbing function and absorbs extra ultravioletradiation which has been transmitted through recording material P. As aresult, it is possible to very consistently reproduce highly fine anddetailed images.

[0169] Recording material P is guided by guide member 6 and moves fromthe front to the back of FIG. 1, utilizing operation of a transportmeans (not shown). A head scanning means (also not shown) allows headcarriage 2 to reciprocate in the Y direction shown in FIG. 1 wherebyscanning of recording head 3, held by head carriage 2, is carried out.

[0170] Head carriage 2 is arranged above recording material P, andhouses a plurality of recording heads 3, described below, matching thenumber of colors employed for printing images onto recording material Pso that ink ejection openings are arranged on the lower side. Headcarriage 2 is arranged in the main body of recording apparatus 1 in suchmanner that reciprocal motion is allowed in the Y direction in FIG. 1.driven by the head scanning means.

[0171] Incidentally, FIG. 1 shows that head carriage 2 houses white (W),yellow (Y), magenta (M), cyan (C), and black (K) recording heads 3.However, in practice, the number of colors of recording head 3, whichare housed in carriage 2, is decided on a need basis.

[0172] In the followings, Yellow recording head is explained as anexample of recording head 3.

[0173] Recording heads 3 eject a photocurable ink (also called anactinic radiation curable ink such as an ultraviolet radiation curableink), which is supplied by an ink supply means (not shown), ontorecording material P from ejection openings, utilizing operation of aplurality of ejection means (also not shown) arranged in its interior.The ultraviolet radiation curable ink (also called UV ink), which isejected from recording heads 3, is comprised of colorants, polymerizablemonomers, initiators, and the like. When exposed to ultravioletradiation, the aforesaid initiators work as a catalyst, whereby curingproperties are exhibited through cross-linking and polymerizationreaction of the aforesaid monomers.

[0174] During scanning in which recording heads 3 move from one end ofrecording material P to the other end thereof along the Y direction inFIG. 1, while driven by the head scanning means, aforesaid recordingheads 3 eject the aforesaid UV ink in the form of ink droplets onto adefinite region (an ink droplet receivable area) of recording material Pand impinge ink droplets onto the aforesaid ink droplet receivable area.

[0175] The aforesaid scanning is carried out at a suitable frequency.The aforesaid UV ink is ejected onto the ink droplet receivable region.Thereafter, recording material P is appropriately conveyed from thefront to the back of FIG. 1, employing a conveying means, and scanningis again carried out employing the head scanning means. During theaforesaid scanning, the aforesaid UV ink is ejected onto the followingink droplet receivable region adjacent to the backward direction of FIG.1, while employing recording heads 3.

[0176] The aforesaid operation is then repeated. By ejecting theaforesaid UV ink from recording heads 3 while synchronizing the headscanning means with the conveying means, an image comprised of anassembly of UV ink droplets is formed on recording material P.

[0177] Exposure means 4 is comprised of an ultraviolet radiation lampwhich emits ultraviolet radiation of a specified wavelength region atconsistent exposure energy, and a filter which transmits the ultravioletradiation of the specified wavelength. Herein, employed as ultravioletradiation lamps may be mercury lamps, metal halide lamps, excimerlasers, ultraviolet lasers, cold cathode tubes, black-light lamps, andLEDs (light emitting diodes). Of these, preferred are band-shaped metalhalide lamp tubes, cold cathode tubes, mercury lamps, or black-lightlamps. Specifically, preferred are cold cathode tubes and black-lightlamps which emit ultraviolet radiation of a wavelength of 365 nm,because bleeding is minimized, dot diameter is efficiently controlled,and wrinkling during curing is minimized. By employing the black lightlamp as a radiation source of exposure means 4, it is possible toprepare exposure means 4 to cure the UV ink at a lower cost.

[0178] Exposure means 4 is shaped to be nearly equal to the maximum onewhich can be set by recording apparatus (being a UV ink-jet printer) 1of the ink dot receivable region in which the UV ink is ejected duringone frequency of scanning in which recording heads 3 are driven by thehead scanning means, or is shaped to be larger than the ink dotreceiving region.

[0179] Exposure means 4 are arranged and fixed on both sides of headcarriage 2, being nearly parallel to recording material P.

[0180] As noted above, as a means to control illuminance in the inkejection section, needless to say, entire recording heads 3 are shieldedfrom light. In addition, it is effective that distance h2 between inkejection section 31 of recording heads 3 and recording material P isadjusted to be greater than distance h1 between exposure means 4 andrecording material P (i.e., h1<h2) and/or distance d between recordingheads 3 and exposure means 4 increases (d increases). Further, it ismore preferable that bellows structure 7 is applied between recordingheads 3 and exposure means 4.

[0181] Herein, it is possible to suitably change the wavelength ofultraviolet radiation which is exposed employing exposure means 4 byreplacing ultraviolet radiation lamps or filters fitted with exposuremeans 4.

EXAMPLES

[0182] The present invention will now be described with reference toexamples. However it is not limited thereto.

[0183] <<Preparation of Ink Composition>>

[0184] Ink compositions having the constitution described in Table 1were prepared. TABLE 1 Ink Composition K C M Y W Colorant ColorantColorant Colorant Colorant Colorant 1 2 3 4 5 Added Amount 4 3 4 3 20Cationic oxetane (OXT- 67 63 67 68 46 Polymerizable 2121, Monomermanufactured by Toagosei Chemical Industry Co., Ltd.) Cationicepoxidated 20 20 20 20 20 Polymerizable compound Monomer (epoxidatedsoybean oil, manufactured by Asahi Denka Kogyo K.K.) Acid Acid 1 1 1 1 1Multiplying Multiplying Agent Agent 1 Thermally Thermally 2 2 2 2 2 BaseBasic Group Generating Generating Agent Agent 1 Photo- CS5102 5 10 5 510 lytically (manufactured Acid by Nippon Soda Generating Co., Ltd.)Agent Initiator Aid CI7001 1 1 1 1 1 (manufactured by Nippon Soda Co.,Ltd.)

[0185] The abbreviations described in Table 1 are as follows:

[0186] K: black ink

[0187] C: cyan ink

[0188] M: magenta ink

[0189] Y: yellow ink

[0190] W: white ink

[0191] Colorant 1: C.I. Pigment Black 7

[0192] Colorant 2: C.I. Pigment Blue 15:3

[0193] Colorant 3: C.I. Pigment Red 57:1

[0194] Colorant 4: C.I. Pigment Yellow 13

[0195] Colorant 5: titanium oxide (anatase type at an average particlediameter of 0.20 μm)

[0196] Acid Multiplying Agent

[0197] Compound 1

[0198] Thermally Base Generating Agent 1

[0199] <<Ink Jet Image Forming Method>>

[0200] The ink jet printer provided with a piezo type ink jet head,shown in Table 1, was loaded with each of the ink composition sets,prepared as above, and image recording was continuously performed oneach of the long recording media at a width of 600 mm and a length of1,000 m, shown in Tale 2. The ink feeding system was comprised of an inktank, a feeding pipe, a pipe arrangement with filters, and a piezo head.Heat was insulated from the pre-chamber ink tank to the head section andtemperature was raised to 50° C. The piezo head was driven so thatmulti-sized dots of 2-14 pl were ejected at a resolution of 720×720 dpi(dpi refers to the number of dots per inch which equals 2.54 cm) andeach ink was continuously ejected. After ink deposition onto therecording medium, curing was performed by exposure to ultravioletradiation. Evaluation was carried out on location conditioned to 23° C.and 40 percent relative humidity.

[0201] The volume of ink liquid droplets per ejection in each of theimage forming methods and duration (exposure timing) between the inkdeposition and the exposure to ultraviolet radiation were controlled asshown in Table 2. TABLE 2 Volume Recording Medium of Image pH of LiquidForming Name of Layer Ink Exposure Method Recording Sur- Droplet TimingNo. Medium face (pl) (seconds) Remarks 1 YUPO: FGS 8.8 2 0.1 Present(manufactured Invention by YUPO Corp.) 2 WP110 8.8 2 0.1 Present(manufactured Invention by Nisshinbo Industries, Inc.) 3 YUPO: GWG 6.2 20.1 Present (manufactured Invention by YUPO Corp.) 4 PET 6 2 0.1 PresentInvention 5 Coated Paper: 7.5 2 0.1 Present OK Coat Invention 6Tarpaulin 7.5 2 0.1 Present Invention 7 YUPO: FGS 8.8 8 0.1 Present(manufactured Invention by YUPO Corp.) 8 YUPO: FGS 8.8 14 0.1Comparative (manufactured Example by YUPO Corp.) 9 Tarpaulin 7.5 14 0.1Comparative Example 10 YUPO: FGS 8.8 2 0.06 Present (manufacturedInvention by YUPO Corp.) 11 YUPO: FGS 8.8 2 2 Comparative (manufacturedExample by YUPO Corp.) 12 Tarpaulin 7.5 2 2 Comparative Example

[0202] Exposure radiation sources and exposure methods are detailedbelow.

[0203] Exposure radiation source: fluorescent lamp (power consumptionless than 1 kw/hour, special order product manufactured by NIPPOElectric Co., Ltd.)

[0204] Exposure method: exposure employing a linear radiation sourcefrom both ends of a recording head

[0205] <<Evaluation of Ink Jet Recording Images>>

[0206] Each of the images recorded by the above-mentioned imagerecording method was subjected to each evaluation below.

[0207] (Evaluation of Color Bleeding=Evaluation of Detail)

[0208] Adjacent dots of each color were enlarged by a hand magnifier,and the degree of bleeding was visually observed. Subsequently, colormixing resistance was evaluated based on the criteria below, and theaverage rank of each color was recorded.

[0209] A: the shape of adjacent dots maintained circularity andexhibited no bleeding

[0210] B: the shape of adjacent dots maintained near circularity andexhibited almost no bleeding

[0211] C: the shape of adjacent dots was slightly deformed due tobleeding, but at the lowest level for commercial viability]

[0212] D: adjacent dots exhibited bleeding and mixing, and were at alevel of no commercial viability

[0213] (Evaluation of Close Adhesion)

[0214] After printing 4C solid images and curing the resulting images,close adhesion was evaluated by peeling adhered Cellotape (a registeredtrade mark).

[0215] A: no peeling was noticed

[0216] B: slight peeling was noticed, but resulted in no problem

[0217] C: peeling was noticed but was at the lowest level of commercialviability

[0218] D: peeling was noticed and was beyond the limit for commercialviability

[0219] (Evaluation of Curing)

[0220] A: ink was completely cured and was not removed by rubbing withfingers

[0221] B: ink was removed by vigorous rubbing with fingers

[0222] C: ink was removed by rubbing with fingers but at the lowestlevel of commercial viability

[0223] D: ink was removed by rubbing and was beyond the limit ofcommercial viability

[0224] Table 3 shows the evaluation results. Incidentally, during imageformation, almost no unpleasant odors due to inks were noticed. TABLE 3Image Close Forming Adhesion Method No. Curability Property DetailRemarks 1 A B A Present Invention 2 A B A Present Invention 3 A A APresent Invention 4 A A A Present Invention 5 A A A Present Invention 6A A A Present Invention 7 B B B Present Invention 8 D D D ComparativeExample 9 C D D Comparative Example 10 A A A Present Invention 11 C D DComparative Example 12 B D D Comparative Example

[0225] Based on the results of Table 3, it was noticed that even in arecording media of a high layer surface pH, highly detailed images whichexhibited excellent adhesion property and curability were preparedemploying the image forming method of the present invention.

[0226] According to the present invention, it is possible to provide animage forming method which forms highly detailed images exhibitingminimal unpleasant odors, as well as excellent adhesion property andcurability, employing general purpose recording media.

What is claimed is:
 1. A method for forming an image with an ink-jetprinter, the ink-jet printer being provided with: (i) a recording headhaving a plurality of nozzles; and (ii) a radiation means to irradiatean ink ejected on a recording media, wherein the method comprises thesteps of: (a) ejecting droplets of the ink from the nozzles on therecording media, provided that: (1) the ink contains a cationicpolymerizable monomer and a photo acid generating agent; (2) therecording media has a surface pH value of not less than 6; and (3) avolume of each droplet is from 2 to 10 pl, (b) irradiating the ejecteddroplets of the ink on the recording media within a period of timebetween 0.01 and 1.0 second after arrival of the droplets on therecording media.
 2. The method for forming an image with an ink-jetprinter of claim 1, wherein the ink comprises a colorant.
 3. The methodfor forming an image with an ink-jet printer of claim 1, wherein therecording media has a surface pH value of not less than
 7. 4. The methodfor forming an image with an ink-jet printer of claim 1, wherein thecationic polymerizable monomer contained in the ink is an oxetanecompound.